This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Brome Mosaic Virus (BMV) protein 1a is a multifunctional RNA replication factor with key roles in assembly and function of viral RNA replication complexes. 1a localizes to perinuclear endoplasmic reticulum (ER) membranes as a peripheral membrane protein, induces ER membrane invaginations in which RNA replication occurs, and recruits BMV 2a polymerase and RNA replication templates to form RNA replication complexes. We identified a peptide in 1a that is critically involved in 1a's functional association with ER membranes. Mutational studies showed that specific residues of the peptide were important for 1a association with membranes. Accordingly, to build on the above results, we will use NMR to determine the three dimensional structure of this peptide and the mechanism of its binding to membranes.